Bladed servers, or bladed computer systems, are computing systems that provision servers or other computer resources on individual cards, or blades. There are many types of blades—processor blades, server blades, storage blades, network blades, etc.—and one or more of each type of blade is typically housed together in a single structure, thus creating high-density computing systems with modular architectures, ensuring flexibility and scalability of the systems, and reducing space requirements. Server blades, along with storage, networking, and other blades, are typically installed in a rack-mountable enclosure, or chassis, which hosts multiple blades. The multiple blades share common resources such as cabling, power supplies, and cooling fans.
The telecommunications industry has been using blade server technology for many years. More generally, the condensed blade server architecture benefits people and businesses that: (1) use the Internet to generate revenue and to provide services to customers; (2) are moving some of their business processes to the Web; and/or (3) need the flexibility to deploy Internet-edge applications in their own data center. Because of recent developments in technology, blade servers are now used for applications such as Web hosting, Web caching, and content streaming.
In Web caching applications, frequently-requested Web content is stored closer to the user, thus allowing for quicker retrieval of objects by the user and reducing the time and bandwidth required to access the Internet. Since companies and individuals are now streaming media (e.g., video and audio) to more effectively communicate both internally and externally, a massive growth of rich media content delivery on the Internet has occurred. Bladed servers are being used to meet the new demands created as a result of this growth.
Though bladed servers provide many advantages, several engineering challenges arise when using bladed servers. Among these challenges is the challenge of designing and operating a bladed system such that sufficient heat is dissipated in the limited space available in the chassis that hosts the system. To address heat dissipation challenges, bladed server systems are designed within an underlying power and thermal envelope. For example, when a chassis that hosts a bladed system has a limited amount of airflow available to cool the blades (i.e., when the system can only dissipate a limited amount of heat), then the chassis is designed for a limited amount of power consumption and an associated limited performance of the blades. Some known power limiting strategies include powering down a CPU functional unit, e.g., a floating-point unit or an on-die cache, or trading off speed for reduced power consumption in a hard drive.
In a system where the ability of the chassis to cool is limited to X and there are Y blades, each blade can only approximately contribute X/Y to the dissipated power in the chassis. Thus, each blade is limited to the performance associated with an X/Y power level.
In a bladed architecture, multiple blades, each representing a separate system, are present in the same chassis. Associated with the chassis are a specific set of power and thermal requirements. Specifically, these requirements put a limit on the amount of power that can be consumed by the blades. This power limitation puts a limitation on the frequency that the processors on the blade can run, and thus limits the performance.
Prior solutions included running all the blades at a performance level less than the blades' maximum in order to meet the overall chassis power and thermal cooling budget. Thus, the performance of each blade is limited to fall within these budgets.